II. Precautions: General pointers
- Sinemet (regular release) is by far the single most effective agent
- This agent should be the first line and main agent used for Parkinsonism
- All other agents are adjuncts only
- Dosing Threshold
- Identify the individual patient's optimal dose and use this dose at each dosing interval
- Using a lower dose below threshold will be inadequate
-
Food Interactions
- Take at least one hour before a meal or 2 hours after a meal
- Wearing off of effect
- See frequency of dosing of Sinemet below
- Most common cause of Insomnia
- May cause anxiety, nocturnal cramps
-
Dyskinesia (e.g. Choreiform movements)
- Dyskinesia is more age related than that of duration of Levodopa use
- Reducing each Levodopa dose decreases this adverse effect
- Amantadine decreases Dyskinesia
- Adverse Effects: Educate patients about serious effects (most are reduced by tapering dose)
- Drowsiness
- Pathologic Gambling, Hypersexuality, Excessive shopping/spending
- Hallucinations or Delusions
- Swelling
III. Preparations
- Carbidopa/Levodopa (Sinemet)
- Preferred option over sustained release
- Lower cost
- Better Pharmacokinetics
- Less Drug Interactions
- Start at 25/100 orally three times daily
- Increase by one tablet every 1-2 days as needed
- Maximum : 3 tablets per dose, three times daily (no benefit to higher doses, but frequency may be increased)
- Frequency of dose
- Initially give dose three times daily
- Long term, dose may wear off early
- Frequency may need to be increased to every 6 hours (at same number of tablets at each dose)
- Preferred option over sustained release
- Carbidopa/Levodopa Sustained release (Sinemet CR)
- Start at 50/200 orally twice daily
- Increase by one tablet every 3 days as needed
- Maximum : 8 tablets daily
- No benefit over immediate release in motor function, and absorption may be sporadic in some patients
- Carbidopa/Levodopa fast onset, sustained release (Rytary)
- Onset within 1 hour, duration of 6 hours
- Start with lowest dose taken 3 times daily
- Costs 3-4 times more than generic Carbidopa/Levodopa
- May decrease "off time", the wearing off of activity between doses
- Consider in advanced Parkinsonism for "off time" problems despite four time daily dosing
- Typical Dose: 3-4 caps three times daily
- Requires higher dosing than other preparations due to lower Bioavailability
- (2015) Presc Lett 22(7): 41
- Carbidopa/Levodopa/Entacapone (Stalevo)
- Start at 12.5/50/200 PO bid
- Increase slowly
- Maximum : 8 tablets daily
- Carbidopa/Levodopa Enteral Suspension (Duopa)
- Convert from immediate release dosing to administer over 16 hours (max daily dose 2000 mg)
- Inbrija (inhaled Levodopa)
- Indicated in off-time motor rigidity or Tremor
- Rapid onset (10 min after inhalation) and duration of 1 hour used for prn "off time" rigidity or Tremor
- Less expensive ($30/dose) than Apokyn ($200/dose), an injectable option for off-time
- Requires dexterity to replace capsule in Inhaler
- Avoid in underlying lung disease (e.g. Asthma, COPD) due to bronchospasm risk
- (2019) Presc Lett 26(5)
IV. Adverse Effects
V. References
- Ahlskog (2011) Mayo Internal Medicine Review Lecture
- Schim (2001) CMEA Medicine Lecture, San Diego
- Clarke (2003) Clin Evid 10:1582-98 [PubMed]
- Clarke (2004) Lancet Neurol 3:466-74 [PubMed]
- Gazewood (2013) Am Fam Physician 87(4): 267-73 [PubMed]
- Halli-Tierney (2020) Amf fam Physician 102(11):679-91 [PubMed]
- Nutt (2005) N Engl J Med 353:1021-7 [PubMed]
- Olanow (2001) Neurology 56:S1-88 [PubMed]
- Rao (2006) Am Fam Physician 74:2046-56 [PubMed]
- Young (1999) Am Fam Physician 59(8):2155-67 [PubMed]
Images: Related links to external sites (from Bing)
Related Studies
carbidopa-levodopa (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
CARBIDOPA-LEVODOPA 10-100 TAB | Generic | $0.14 each |
CARBIDOPA-LEVODOPA 25-100 TAB | Generic | $0.11 each |
CARBIDOPA-LEVODOPA 25-250 TAB | Generic | $0.14 each |
CARBIDOPA-LEVODOPA-ENTACAPONE 25-100-200 MG TAB | Generic | $0.73 each |
CARBIDOPA-LEVODOPA-ENTACAPONE 31.25-125-200 MG TAB | Generic | $1.05 each |
CARBIDOPA-LEVODOPA-ENTACAPONE 37.5-150-200 MG TAB | Generic | $0.80 each |
CARBIDOPA-LEVODOPA-ENTACAPONE 50-200-200 MG TAB | Generic | $0.92 each |
rytary (on 7/20/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
RYTARY ER 23.75 MG-95 MG CAP | $3.70 each | |
RYTARY ER 36.25 MG-145 MG CAP | $3.70 each | |
RYTARY ER 48.75 MG-195 MG CAP | $3.74 each | |
RYTARY ER 61.25 MG-245 MG CAP | $4.61 each |